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Demonstration task - Motor protection with MODBUS TCP
Berčík, Dominik ; Drahota, Petr (referee) ; Štohl, Radek (advisor)
The purpose of this bachelor work is to design and implement the demostration panel for laboratory task in which asynchronous motor failures will be simulated. These will be evaluated using the intelligent electronic device REF615, which communicates via ModBus/TCP, and compared with the values of the motor protection E1 plus 193-EECB and the Power Flex 525 AC. Both devices communicate by Ethernet/IP. A part of the work is an analysis of functionality of used components including their configuration and description of communication protocols ModBus/TCP and Ethernet/IP.
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Mineralogy of manganese (hydr)oxides formed by weathering of Mn carbonates at the Kutná Hora ore district
Veselý, Adam ; Drahota, Petr (advisor) ; Tuhý, Marek (referee)
The thesis deals with the geochemisty and mineralogy of manganese oxides and hydroxides. The thesis describes chemical, physical and mineralogical properties of manganese oxide minerals. The main objective of the experimental part of the thesis is to try to identify oxide minerals of manganese, which are formed on carbonate veins in the Kutná ore district. The methods used in the practical part are X-ray diffraction and Raman spectrometry. Most of the studied minerals are characterized by broad diffraction reflections, indicating their low crystallinity. These phases most commonly correspond to the mineral todorokite and less commonly to rancieite, manganite and cryptomelane. In conclusion, it appears that several new mineral species have been identified for the Kutná Hora ore district, but the interpretation of these phases was itself quite problematic and the results contain a considerable degree of uncertainty.
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Arsenic speciation in mining wastes - case studies in systems dominated by ferric sulfoarsenates
Jelenová, Helena ; Drahota, Petr (advisor) ; Filippi, Michal (referee) ; Jurkovič, Ľubomír (referee)
The aim of the thesis is to study behavior and mineralogy of arsenic in mine wastes with high levels of FeIII and SVI . Three methodological studies are related to (i) identification and characterization of secondary arsenic phases using a Raman spectrometry, (ii) chemical fractionation of arsenic in mine waste materials as observed by optimized sequential extraction, (ii) and investigation of thermodynamic properties of zýkaite. The mineralogy and mobility of arsenic was studied in mine waste material of five dumps located at three sites (Kaňk near Kutná Hora, Jedová jáma near Vejprty, and Dlouhá Ves) and in stalactite samples from two abandoned underground mines (Plavno and Mikulov near Teplice). Mineralogical and geochemical characterization of samples included standard methods and techniques. Chemical composition of solid and liquid (pore water, leachates) samples was performed using a XRF, ICP OES, ICP MS, etc. X-ray diffraction, Raman spectrometry and electron microscope equipped with microanalysis were the most frequent techniques used for mineralogical characterization of the solids. The results showed that the speciation of arsenic in the solid phase significantly varied among the studied sites and was a function of total concentration as well as proportion of the major components of...
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Speciation of arsenic under reducing conditions of organic-rich soil
Peřestá, Magdaléna ; Drahota, Petr (advisor) ; Hiller, Edgar (referee) ; Doušová, Barbora (referee)
The PhD thesis deals with arsenic speciation under reducing conditions of soil with elevated content of organic matter. This issue has been studied in two wetland soils located in two geochemical As anomalies near the villages of Mokrsko and Smolotely (CZ). Speciation and mobility of As was studied in four experiments using a range of mineralogical (XRD, SEM/EDS, EMPA, Raman microspectroscopy) and geochemical (XRF, chemical extraction, pore water analysis) methods. Other methods used in this work included S isotopes and microbial community analysis. The results indicate that the formation of authigenic As sulfides (realgar and bonazziite) is relatively common mechanism of As sequestration in reducing conditions of wetland soils. The sulfides are formed in highly reducing organic-rich microenvironments, where microbial production of dissolved sulfide is sufficiently fast compared to water flow velocity and related slow solute transport. In these microenvironments, Fe sulfides are the first precipitates; As sulfides precipitate after the depletion of Fe2+ in the pore solutions. This phenomenon was well evidenced in the long-term incubation experiment. Results of this experiment also showed that newly formed As sulfides can form in environments with variable concentrations of As and Fe in groundwater....
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Thermal behaviour of selected arsenic minerals/phases and its environmental implications
Stonová, Kateřina ; Tuhý, Marek (advisor) ; Drahota, Petr (referee)
iii ABSTRACT This bachelor's thesis focuses on the thermal behaviour of the following arsenic-bearing minerals: enargite (Cu3AsS4), realgar (As4S4), orpiment (As2S3), mimetite [Pb5(AsO4)3Cl] and conichalcite [CaCu(AsO4)(OH)]. Additionally, the behaviour of a synthetic analogue of realgar and an organoarsenic compound (cacodylic acid) was investigated. The experiments were conducted in an argon atmosphere and the temperature range 20-800 řC, with a linear temperature increase. Emissions of arsenic and other elements (S and Pb) were detected using ICP-OES. The thermal behaviour was further analysed by simultaneous DSC and TGA, and the mineralogical composition of the residues was determined by X-ray diffraction analyses. The least stable minerals were realgar and orpiment, melting at 300-320 řC and subsequently releasing arsenic and sulphur (with the highest release at 400-450 řC). Enargite decomposed in the studied temperature range with a 40 % mass loss, emitting the most arsenic and sulphur around 600 řC. Conichalcite also underwent decomposition, losing ca. 3 % of mass and releasing arsenic especially around 700 řC. Mimetite proved the most stable, losing almost no mass and starting to emit arsenic, simultaneously with lead, near the upper limit of the temperature range. The results align with previously...
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Anomalous occurrences of arsenic in soils of the Czech Republic
Svoboda, Ondřej ; Drahota, Petr (advisor) ; Hojdová, Marie (referee)
This thesis aims to evaluate the anomalous concentrations of arsenic in soils (>30 mg/kg) of the Czech Republic. Anomalous concentrations are mainly caused by combustion of fossil fuels, mining operations and weathering of arsenic-rich rocks. The largest part of contaminated soil in CR is related to the combustion of arsenic-rich lignite, and includes, e.g., the area of Ore Mountains. The highest concentrations of arsenic in soil of CR are up to thousands of mg/kg. For example, soil adjacent to the Kutná Hora ore district contained up to 6 890 mg/kg of As. Such a high concentrations are due to mining operations. Beside anthropogenic sources, weathering of arsenic-rich rocks at Mokrsko has resulted in anomalous concentrations in soil that may attain up to 2 890 mg/kg.
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Treatment of mine waters rich in arsenic
Řáhová, Jaroslava ; Drahota, Petr (advisor) ; Kindlová, Helena (referee)
Summary: This bachalor thesis deals with treatment of mine waters rich in arsenic. First part is an overview of decontamination methods used for elimination of arsenic from water. Emphasised parts are focused on arsenic adsorption on Fe-oxides and hydroxides, particles which may be formed in mine waters; as well as on ODAS treatment system, widely used for mine waters decontamination. The experimental part is a study of decontamination process at mine treatment plant waters in Kaňk, Kutná hora. Extremely high concentrations of arsenic (77,72 mg/L) are found in acid mine drainage from closed Turkaňk mine. Results of this thesis signifies incorporation of arsenic and other elements dissolved in mine water into secondary forming Fe-oxyhydroxides within decontamination process.
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Speciation of arsenic in a historical mine wastes
Knappová, Magdaléna ; Drahota, Petr (advisor) ; Jurkovič, Ľubomír (referee)
There are many locations with historical mining wastes around the world that contain high concentrations of pollutants and harmful elements. Mineralogical composition of those wastes has a major impact on release and later migration of dangerous elements into surrounding environments, resulting in potential environmental risk. Goal of this master thesis is to characterize mobility and major sinks of arsenic in 50-years-old mining waste materials at Jedová mine near Vejprty and Dlouhá Ves mine near Havlíčkův Brod. For this purpose, solid waste and pore water samples were collected from both mining waste dumps. Solid samples were analysed by mineralogical (XRF, XRD, SEM-WDS and Raman microspectroscopy) and geochemical (sequential extraction) methods, while pore water samples were analysed using IPC-MS (cations), HPLC (anions) and spectrophotometry (Fe3+/Fetot species). Arsenopyrite is the primary source of As at both localities. In the mining waste at Jedová jáma mine, As precipitates predominantly as amorphous ferric arsenate (HFA) and is also accumulated in scorodite and Fe (hydr)oxide (up to 3.2 wt.% of As2O5). In Dlouhá Ves, due to weathering of large amount of sulphides (sphalerite, chalcopyrite, galena, pyrite and pyrrhotite), acidic conditions prevail (pH ~ 2.7). Under this pH, the major part...
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Bioavailability of arsenic in the mine waste in Kaňk near Kutná Hora
Raus, Karel ; Drahota, Petr (advisor) ; Vítková, Martina (referee)
Summary: Arsenic relative bioavailability (RBA) in mine wastes is always lower than 100%. Total concentration of As at Kaňk varied between 87 and 15500 mg.kg-1 in collected samples of road dust, urban soil and mine waste, however the bioaccessible amount of arsenic obtained with SRBC-G method was much lower (6-795 mg.kg-1 ). Crucial factors influencing arsenic bioaccessibility are pH value and solubility of mineral phases which are stable under given conditions of the sample. Although the highest total As concentrations were found in the mine wastes (9250-15500 mg.kg-1 ), these samples displayed the lowest As bioaccessibilities (5,1 ± 1,3%). This is probably due to the prevalence of poorly soluble Fe- arsenates and As-sulfides in the low-pH mine wastes. In the near-neutral samples of road dust and urban soil the As bioaccessibility showed slightly higher values (7,5 ± 2,6%; 8,2 ± 2,6% respectively). From the chemistry and mineralogy of the samples it is possible to recognize the mine wastes as the main source of As contamination in soil and road dust at the Kaňk village. The bioaccessibility of arsenic and other pollutants from the specific site provides more accurate data for the health risk assessment, although the valid in vivo/in vitro comparison doesn't seem to be revealed.
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Arsenic Contamination of Waters in the World
Grecká, Marie ; Bendl, Jiří (advisor) ; Drahota, Petr (referee)
Summary: In this bachelor thesis there are summarized reasons of occurrence of too high As concentration in groundwater abroad and possibilities of the water treatment. There are mentioned mainly the Asian countries, where there were proved the cases of serious diseases of inhabitants in connection with long-term consumption of the water from the shallow groundwater in the area of big river deltas. Arsenic is released to the groundwater from the iron oxides by natural process in reductive environment (due to the oxidation of organic matter). In the arid climate areas in Asia or South America, there are also localities of high As groundwater. The groundwater in these arid areas is more saline and the reason of high As concentration there is the oxidation of sulphide minerals. Then there are given the other examples of arsenic release by the oxidation of pyrite in the gold (or tin) mining areas etc. Another source of arsenic in water is a geothermal system. A suitable method for the arsenic removal from water is a coprecipitation of iron and As (V).
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